DSM-IV pain disorder in the general population An exploration of the structure and threshold of medically unexplained pain symptoms Christine Fröhlich,· Frank Jacobi, Hans-Ulrich Wittchen Received: 18 March 2005 / Accepted: 12 September 2005 / Published online: 18 November 2005 Abstract Background Despite an abundance of questionnaire data, the prevalence of clinically significant and medically unexplained pain syndromes in the general population has rarely been examined with a rigid personal-interview methodology. Objective To examine the prevalence of pain syndromes and DSM- IV pain disorder in the general population and the association with other mental disorders, as well as effects on disability and health-care utilization. Methods Analyses were based on a community sample of 4.181 participants 18–65 years old; diagnostic variables were assessed with a standardized diagnostic interview (M-CIDI). Results The 12-month prevalence for DSM-IV pain disorder in the general population was 8.1%; more than 53% showed concurrent anxiety and mood disorders. Subjects with pain disorder revealed significantly poorer quality of life, greater disability, and higher health-care utilization rates compared to cases with pain below the diagnostic threshold. The majority had more than one type of pain, with excessive headache being the most frequent type. Conclusions Even when stringent diagnostic criteria are used, pain disorder ranks among the most prevalent conditions in the community. The joint effects of high prevalence in all age groups, substantial disability, and increased health services utilization result in a substantial total burden, exceeding that of depression and anxiety. Key words: DSM-IV pain disorder, pain syndromes, comorbidity, impairment, Composite International Diagnostic Interview (CIDI) Introduction Chronic pain is well known as a highly prevalent condition in the general population. However, population-based prevalence studies have provided only incomplete and quite inconsistent epidemiological characterization. For example, prevalence rates of pain vary from 2%–50% for the general population depending on varying methodological factors [48].Table 1 presents core results along with basic methodological information from recent epidemiological studies focussing on community surveys. Beyond “true” prevalence differences (e. g., due to cultural and ethnical factors [17]), this variability of prevalence rates can be largely attributed to critical issues in the assessment of pain and mental disorders in general, such as the conceptual level (coverage, symptoms vs. diagnosis), the time frame (e. g., 12 month vs. lifetime), and the assessment method (e. g., questionnaire vs. interview) [54, 55]. Because of the complex nature of pain, the development of a comprehensive and coherent theoretical framework for chronic pain and a universally applicable and accepted classification system has proven difficult [29].As a result, there is also no universally accepted diagnostic instrument for epidemiological research in this domain. In the development of the Diagnostic and Statistical Manual of Mental Disorders (DSM) [2–4], the diagnostic criteria of pain were tentatively specified and revised several times and finally labelled “pain disorder” in DSM-IV as a primarily descriptive and not etiological term. The specification also allowed for the first time the development of a standardized diagnostic interview approach to assess and clinically evaluate pain, but representative epidemiological studies using DSM-IV criteria are still not available [14]. The inclusion of a pain assessment module in recent diagnostic instruments, such as CIDI, also allows examination with greater precision of correlates and patterns of comorbidity with other mental disorders. The association of pain with other mental disorders, particularly depression, has been of interest for many years. Prevalence rates of major depression in pain patients range from 18%–54% [6, 13, 14, 36], compared to 2%–8% in the general population [e. g., 28, 51, 52]. The increasing prevalence of chronic pain is associated with an increasing number of depressive symptoms; in addition, nearly every second respondent diagnosed with major depression reports also experiencing pain [40]. Bair et al. [5] point out that the presence of depression in pain patients is associated with more pain complaints and greater impairment and that the presence of pain in depressive patients effects quality of life, occupational functioning, and health-care utilization. Findings with regard to the chronological order of pain and comorbid conditions are heterogeneous. Fishbain et al. [18] reviewed 83 clinical and epidemiological studies with regard to several hypotheses on the comorbidity of pain (e. g., antecendent, consequence, or cognitive-mediation hypothesis).According to this review, pain precedes depression in most comorbid cases (i. e., there is stronger evidence for depression as a consequence of pain). Prospective studies indicate a bidirectional association, rather than a simultaneous beginning [e. g., 11, 35, 37]. Less attention is paid to comorbidity with anxiety disorders although data imply an association at least as strong as that which occurs with depression [38, 49]. Because of these inconsistent findings, the inconsistent definitions of “chronic pain”, and the absence of representative studies using DSM-IV criteria for pain disorder, the aims of the present study were to examine (1) the prevalence of clinically significant and medically unexplained pain symptoms as well as of DSM-IV pain disorder in the general population; (2) the type and strength of associations of pain symptoms/DSM-IV pain disorder with mood, anxiety, and substance disorder; and (3) the association with disability days, quality of life, and health-care utilization. Methods Findings are based on the Mental Health Supplement of the German National Health Interview and Examination Survey 1998/99 (GHSMHS). Aims, design, and methods have been described in greater detail elsewhere [8, 26].Therefore, design and sample characteristics are only briefly discussed here. Sample The GHS covered a range of medical and social assessments in a multistage stratified random sample of the general German population from 18 to 79 years of age, drawn from population registries (N=7.124; response rate: 61%). The mental health supplement covered a subsample of this population (N=4.181; response rate within that subsample: 87.6 %) and can be regarded as representative for the German non-instutionalized adult population from 18 to 65 years of age. GHS respondents older than 65 years were excluded because of unsatisfactory psychometric properties of the diagnostic interview for use in older populations [30]. Assessment The assessment of mental disorders was based on the computer-assisted version of the Munich Composite International Diagnostic Interview (DIA-X/M-CIDI; [57, 59]), administered by clinically trained interviewers (psychologists and MDs). The M-CIDI is a fully structured interview that allows the assessment of symptoms and syndromes, as well as 4-week, 12-month, and selected lifetime diagnoses of a wide range of mental disorders, based on DSM-IV [4] and ICD- 10 [60]. Psychometric properties of the M-CIDI were found to range from “acceptable” to “very good” [32, 42, 56, 59].All subsequent analyses were performed for 12-month criteria. Pain symptoms and DSM-IV pain disorder. Diagnostic criteria for DSM-IV pain disorder are presented in Table 2. In the M-CIDI, first the presence of the following painful conditions in the past 12 months was assessed: excessive abdominal pain, excessive back pain, joint pain, limb pain, chest pain, excessive headache, excessive painful menstruation, rectal and genital pain, and other pain. Whenever the respondent acknowledged having experienced at least one of these pain types, the interviewer entered a standardized complex set of probe questions to evaluate the nature of the complaint [45, 58].There are several levels of probing before the symptom ultimately is considered “medically unexplained”. The probe questions started with establishing clinical severity with respect to significance (criterion A [4]).A symptom was considered clinically significant if any of the following conditions are met: (1) the symptom prompts help-seeking behavior with a medical doctor or (2) another health professional; (3) medication was taken more than once for it; or (4) the symptom interfered substantially with life or activity. The next probe questions targeted whether any somatic/substance- related factors might explain the occurrence of the symptom. If there was at least one significant occasion where the symptom was not entirely explained by medical diagnosis, use of medication or drugs, injuries, or combinations of these, the symptom was rated as unexplained (or somatoform). If at least one painful condition was found to be present as clinically relevant, further questions were asked to assess the diagnosis of DSM-IV pain disorder (criterion B [4]): (1) Did the pain ever last for a period of at least six months? (2) Did the pain ever prevent you for a period of six months from meeting your friends and family and from doing your work? (3) How strongly did the pain interfere with your life and activities (a little, a lot, or very much)? If the respondent acknowledged impairment for six months or at least a substantial interference with daily living, the diagnosis of DSM-IV pain disorder was given. For the main diagnostic